An Ernst & Young (EY) report commissioned by Michelin has found that – within the European Union most tyres are replaced at 3mm. Indeed, citing a study published in 2014 in the journal Tire Science and Technology, the report writers found that the average and median tread depths of removed tyres are 3.1 and 3mm respectively. The publication came in parallel with a Michelin demonstration on tread depth at its Ladoux R&D facility in France, in mid-May.

But the report also found that changing tyres at 3mm instead of 1.6mm “is not inevitable” and such a move would cost EU drivers an extra 6.9 billion euros a year in “unnecessary tyre purchases and additional fuel consumption.”

Written under the heading “Planned obsolescence is not inevitable: Environmental and social impacts related to the generalisation of the removal of tyres at 3mm tread depth across the European Union”, the EY report found that in practice European drivers are incentivized to change their tyres at 3mm by some stakeholders. The problem, from the report’s perspective, is that it is “difficult for motorists to assess the exact performance of their tyres throughout the entire lifespan”.

Furthermore, the EY report argues that accident data is not conclusive when it comes to supporting a regulatory change from 1.6mm minimum tread depth to 3mm. Citing a 2014 TNO report for the European Commission, it said: “The accident data used in the current study however indicates no benefit in terms of reducing the number of accidents by increasing the minimum tread depth…The results of the study suggest that 1.6mm could be a suitable level based on existing national legislation in member states.”

There was even the suggestion that changing at 3mm could push consumers towards budget tyres: “In case of an increase of the minimum tread depth, tyres have to be replaced more often. The resulting increase in costs can lead vehicle owners to not invest in tyres with a long-term performance due to budget constraints. If tyres with a short-term performance are preferred due to cost considerations this will negatively impact driving and traffic safety”, according to Thomas Burkhard, vice president of VUFO (an institute for Traffic Accident Research).